Considerations for scale-out file servers

Scale-out file servers can significantly lower storage costs, but it might not be right for organizations. Here's what to consider.

Scale-out file servers (SOFs) are Windows Server 2012 machines that are members of a failover cluster that all share cluster shared volumes and offer up the same shares regardless of which actual server is talking with the client over the network. They are a great solution because they lower storage costs significantly by removing the need to purchase name brand storage area network hardware. You can piece together an overarching storage solution using hardware you already have, get transparent failover, and use familiar management tools to make your administration work quick and easy.

But in the goodness that is the description of the features, many IT folks have difficulty seeing the forest for the trees. How does a scale-out file server solution fit in, both against other storage features in Windows Server and as part of your overall storage architecture? What investments do you need to make to fully execute a storage strategy that includes SOFs? Let us take a look at several considerations.

Invest in InfiniBand

If you want to start implementing SOFs right now, look into InfiniBand. While cheap solutions and basic scale-out file server configurations start with SMB 3.0 over Ethernet, where you start really getting into the high performance and high I/O operations per second (IOPS) count is with InfiniBand. InfiniBand is a high bandwidth connection with extremely low latency. Typical commodity InfiniBand network adapters from manufacturers like QLogic go for between $300 and $400 and are capable of reaching 40 gigabits per second transfer speeds. Pair this with an InfiniBand switch from Mellanox -- one of the current giants that control the protocol along with Intel, which retails a good bit under $2,000 -- and you have an extremely high performance storage fabric that leaves your existing Ethernet network untouched.

Consider using Storage Spaces with SOFs

Storage Spaces is essentially software defined storage. By using commodity hardware with a Just a Bunch of Disks setup you could build a storage solution that was pooled, fault tolerant and performant up to a level. You can also tier content between solid state drives and traditional spinning media hard disks so that the most often opened and written to content can live on the fast SSD tier and the archived content and rarely used data can live on the cheaper and bigger but slower spinning disks. Storage Spaces also lets you pool disks together and create resiliency configurations on them like mirroring the disks or creating parity and striping a la RAID.

When you combine Storage Spaces with a scale-out file server solution, then you get a storage architecture that can serve both Windows with SMB 3.0, and Linux or Unix clients as well with NFS, in addition to other storage technologies using iSCSI. And you can scale out as many as up to eight node SOFs clusters as you want, and with Storage Spaces layered on top, you can expose storage to basically any protocol you have in use on your network, without respect to the client. In addition, with Windows Server 2012 R2 you can turn on data deduplication on cluster shared volumes and save up to 90% of your disk space for virtual desktop infrastructure deployments that are using that shared storage.

Remote Direct Memory Access

RDMA might be the best-kept secret in Windows Server and SMB 3.0. It allows the network interface card (NIC) to shuttle data to and from different hosts’ memory without using the data buffers in the operating system—so you are leaving out the host CPU, the host disk storage subsystem, the host timer issues, and anything else, in essence writing directly to the RAM on a machine. InfiniBand is one such application of RDMA, but there is also an RDMA implementation in Windows Server with compatible NICs that works right over regular Ethernet. When using RDMA, you get fast data transfer without spending a ton of money on specialized hardware, making an overall scale-out file server solution even more appealing from a functionality perspective and the point of view of your organization’s checkbook.

Put simply, your strategy going forward when it comes to storage should be to leverage all of the software features of SOFs and Storage Spaces to lower your storage costs as much as possible. When purchasing new hardware, insist that it have RDMA capable storage network adapters or begin immediately with InfiniBand. Spec out new purchases with trusted platform modules to enable future disk encryption capabilities relating to SOFs. Use Storage Spaces in conjunction with SOFs to increase client access capabilities and improve reliability and performance.

Ultimately, with the resilience of the software and the lower hardware costs that come from using off the shelf disks and network hardware, many organizations will find they can buy two and three times the storage space and IOPs for the same amount of money they were spending on EMC, NetApp and other name brand storage solutions. And saving money while getting more? Definitely a good strategy.

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